Faulty unit clients responsibility

Client for more than 4 years need to constantly contact them to check if device is working, I needed a certificate to prove I have a working tracking unit in my vehicle and Tracetec were unable to give me one as the unit was not working anymore! No one from Tracetek contacted me in order to check faulty unit but they keep taking money every month for something that is not working. Takes more than 2 weeks for feedback from Tracetek and o we apologize is all I get but if my vehicle was stolen the tracking unit was my issue because as per Tracetek the client needs to do a constant check to see of everything is working, what are we paying them for then?